Fix Spotless violation

Author: marcphilipp

documentation/src/test/kotlin/example/KotlinCoroutinesDemo.kt

@@ -14,9 +14,13 @@ import org.junit.jupiter.api.BeforeEach
 import org.junit.jupiter.api.Test
 
 // end::user_guide[]
+// @formatter:off
 @Suppress("JUnitMalformedDeclaration")
 // tag::user_guide[]
 class KotlinCoroutinesDemo {
+ // end::user_guide[]
+ // @formatter:on
+ // tag::user_guide[]
  @BeforeEach
  fun regularSetUp() {
  }

gradle/plugins/common/src/main/kotlin/junitbuild.spotless-conventions.gradle.kts

@@ -58,6 +58,7 @@ spotless {
 licenseHeaderFile(license.headerFile)
 trimTrailingWhitespace()
 endWithNewline()
+toggleOffOn("formatter:off", "formatter:on")
 }
 }